== 和 equals()的区别

 

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package com.liaojianya.chapter1; /**  * This program demonstrates the difference between == and equals().  * @author LIAO JIANYA  * 2016年7月20日  */ public class CompareObject {     public static void main(String[] args)     {         String s1 = new String("java");         String s2 = new String("java");         String s3 = s2;         String s4 = new String("JAVA");         //the use of ==         if(s1 == s2)         {             System.out.println("s1和s2堆内存地址一样");                       }         else         {             System.out.println("s1和s2堆内存地址不一样");         }         if(s2 == s3)         {             System.out.println("s2和s3堆内存地址一样");         }         else         {             System.out.println("s2和s3堆内存地址不一样");         }                   //the use of equals()         if(s1.equals(s2))         {             System.out.println("s1和s2内容一样");         }         else         {             System.out.println("s1和s2内容不一样");         }         if(s1.equals(s4))         {             System.out.println("s1和s4内容一样");         }         else         {             System.out.println("s1和s4内容不一样");         }     }   }

　　运行结果：

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s1和s2堆内存地址不一样 s2和s3堆内存地址一样 s1和s2内容一样 s1和s4内容不一样

　　分析：==是用于比较两个对象的内存地址值（引用值）是否相等；equals()方法是用于比较两个对象的内容是否一致。